- Isolation of 6-hydroxy-L-tryptophan from the fruiting body of Lyophyllum decastes for use as a tyrosinase inhibitor
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Tyrosinase is the key enzyme that controls melanin formation. We found that a hot water extract of the lyophilized fruiting body of the fungus Lyophyllum decastes inhibited tyrosinase from Agaricus bisporus. The extract was fractionated by ODS column chromatography, and an active compound was obtained by purification through successive preparative HPLC using an ODS and a HILIC column. Using spectroscopic data, the compound was identified to be an uncommon amino acid, 6-hydroxytryptophan. 6-Hydroxy-L-tryptophan and 6-hydroxy-D-tryptophan were prepared through a Fenton reaction from L-tryptophan and D-tryptophan, respectively. The active compound was determined to be 6-hydroxy-L-tryptophan by comparison of their circular dichroism spectra and retention time on HPLC analysis of the Nα-(5-fluoro-2,4-dinitrophenyl)-L-leuciamide derivative with those of 6-hydroxy-L-tryptophan and 6-hydroxy-D-tryptophan. A Lineweaver-Burk plot of the enzyme reaction in the presence of 6-hydroxy-L-tryptophan indicated that this compound was a competitive inhibitor. The IC50 values of 6-hydroxy-L-tryptophan was 0.23 mM.
- Ishihara, Atsushi,Sugai, Naomi,Bito, Tomohiro,Ube, Naoki,Ueno, Kotomi,Okuda, Yasuhito,Fukushima-Sakuno, Emi
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- SYNTHESIS OF (S)-6-HYDROXYTRYPTOPHAN AND DERIVATIVES THEREOF
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The present invention relates to novel methods and compounds for synthesizing amanitin derivatives. The invention in particular relates to methods for synthesizing (S)-6-hydroxy-tryptophan derivatives which can be used as building blocks for synthesizing
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Page/Page column 26-27
(2020/07/07)
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- Directed evolution of the tryptophan synthase β-subunit for stand-alone function recapitulates allosteric activation
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Enzymes in heteromeric, allosterically regulated complexes catalyze a rich array of chemical reactions. Separating the subunits of such complexes, however, often severely attenuates their catalytic activities, because they can no longer be activated by their protein partners. We used directed evolution to explore allosteric regulation as a source of latent catalytic potential using the β-subunit of tryptophan synthase from Pyrococcus furiosus (PfTrpB). As part of its native αββα complex, TrpB efficiently produces tryptophan and tryptophan analogs; activity drops considerably when it is used as a stand-alone catalyst without the α-subunit. Kinetic, spectroscopic, and X-ray crystallographic data show that this lost activity can be recovered by mutations that reproduce the effects of complexation with the α-subunit. The engineered PfTrpB is a powerful platform for production of Trp analogs and for further directed evolution to expand substrate and reaction scope.
- Buller, Andrew R.,Brinkmann-Chen, Sabine,Romney, David K.,Herger, Michael,Murciano-Calles, Javier,Arnold, Frances H.
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p. 14599 - 14604
(2015/12/05)
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